Okay, true, Titan is off-topic here but still I can't pass up an opportunity to mention a paper that was published today in Geophysical Research Letters (in which I am second author of) reporting the discovery of active playa in the south polar region of Saturn's moon Titan. We also released a press release on this. While counting and measuring dark features in the south polar region last year in preparation for a Titan paper, I found that some of these features were in one observation from June 2005 but not in the other from July 2004. If these were small features, I could discount them as being due to resolution effects and the effects of the atmosphere that blurs out details, but these changes were much too large. You can see what I am talking about on the Planetary Photojournal.
It didn't take us long to figure out what we were looking at, a real surface change on the surface. We surmise that this change resulted from a rainstorm that dumped enough rain over this spot on Titan to flood the valley floors with a shallow layer of liquid methane. The most likely storm (that we are aware of, keep in mind that we don't have continuous coverage) to have caused this was a massive storm system seen from Earth and by Cassini ISS in early October 2004. The brightest part of the storm (and plausibly the most intense part of the storm with the greatest cloud heights) was located over this surface change in the ISS observation of the storm on October 8, 2004.
Anyways, even though it was off-topic, I thought I would quickly share this here.
Link: Cassini Finds Hydrocarbon Rains May Fill Titan Lakes [ciclops.org]